Malhotra, Pawan KumarKaura, Varun2018-01-102018-01-102017http://krishikosh.egranth.ac.in/handle/1/5810039155Transgenic sugarcane plants of variety CoJ88 augmented with DREB1A transgene were screened physiologically to test the susceptibility and tolerance for abiotic stresses (drought, cold and salt). The PCR positive plants (Twenty-two sugarcane lines) grown in pots were subjected to drought stress at grand growth phase and evaluated physiologically (viz. Chlorophyll content, Relative water content (RWC) and Chlorophyll fluorescence) in TC1 stage (Tissue culturally generated clonal stage 1). The values for chlorophyll content exhibits a variation of (1.78-7.72) in transgenic lines as compared to control plants (1.07) whereas chlorophyll fluorescence shows a minimal effect of drought stress in transgenic lines (0.694-0.755) with respect to control plants (0.628). On the basis of aforementioned parameters six (96, 93, 90, 82, 59 and 108) best-performing lines were selected for sowing in next stage. The selected lines were subjected to drought and salt stress (50 mM, 75 mM, 100 mM, 200 mM and 300 mM). After the appearance of stress symptoms (chlorosis, wilting, leaf rolling and necrosis) the physiological and biochemical parameters (Proline and LPO content) were recorded. In TC2 stage (Tissue culturally generated clonal stage 2) transgenic plants demonstrate a nominal effect of salt (1.16-1.61) and drought (1.10-1.49) stress on chlorophyll content values as compared to control (1.03 for salt stress and 0.9 for drought stress) plants. The MDA content varies from (3.57-6.02) under salt and (4.72-7.08) drought stress in transgenic lines with respect to control plants (4.97 for salt stress and 5.93 for drought stress). Three transgenic lines (93, 82 and 96) reveal a higher increase in proline content (4417.5, 2816.8 and 3965.3) under salt stress. On the basis of above-mentioned parameters, three transgenic lines (93, 82 and 96) subjected to drought, salt, and cold stress were selected for molecular studies at RNA level through reverse transcription-PCR by using DREB1A gene specific primers. The quantitative gene expression study was done by using fifteen different stress responsive genes p5CS1, APX1, CAT, GST, HSP, LEA, NAC1, NAC5, NAC6, SOD, NHX1, NFY, NCED, ERA1, and SOS1. In contrast to proline estimation, p5CS1 gene reveals an up-regulation of 65.2 fold and 61.1 fold in transgenic plants subjected to salt and drought stress respectively. Some other genes that showed an up-regulation in transgenic plants subjected to salt and drought stress were CAT, NAC1, NAC5, NHX1 and SOS1.ennullThesis